Speed of Y-wings in the Battle of the Kaliida Nebula

[Who is like God arbour]

In the third Star Wars - The Clone Wars episode, "Shadow of Malevolence", we see a wing of Y-wings attacking the Malevolence.

Under heave fire, the pilots of the Y-wings are trying to cover the length of the Malevolence to reach the bridge, where General Grievous is supposed to be.

Assuming, that the whole ship is maximal 8 km long, the Y-wings would have been extraordinary slow for space vehicles. They have needed several seconds, in which several Y-wings were shot down.

• • 

That would mean, that these Y-wings were far far slower than 8 km/s. And 8 km/s is round about the speed of the US space shuttle in orbit.

There doesn't seems to be a plausible reason, why the pilots of these Y-wings would fly slower than slow to allow to be shot down by the guns of the Malevolence. The plausible conclusion would have to be, that these Y-wings are not able to achieve higher speeds.

Any comments, objections or agreements?

[Mike DiCenso]

There are a couple of ways of looking at the problem. First we can assume that the Malevolence was heading towards the medical station at a given velocity. Two the Y-wings were intercepting the monster ship head-on and therefore the starfighters not only need to accelerate initially towards their target, but then decelerate, and maintain a velocity relative to the Seperatist ship, much as Rebel X-wings and Y-wings would do 20 years later with their interception and attack on the Death Star.
-Mike

[l33telboi]

Only thing that matters in space is acceleration and deceleration, velocity is not as important. You need to remember that these vessels are piloted by humans, they can't zip by the Malevolence at near lightspeed, because then they wouldn't have time to react.

Of course we're also given some insight on maximum acceleration in the same episode. Anakin is trying to escape the advancing Ion blast and tells his men to give it all they've got, as they try to fly their ships out if said weapon's trajectory. But acceleration was not anywhere near the kilo-g area.

[Mr. Oragahn]

One of the highest accelerations is when Anakin joins the V-19 squadron, before attacking the six Munificents.
That said, pinch of salt with that cartoonesque CGI stuff. We've seen characters like Padmé do some weird fu.

[Mike DiCenso]

Only thing that matters in space is acceleration and deceleration, velocity is not as important. You need to remember that these vessels are piloted by humans, they can't zip by the Malevolence at near lightspeed, because then they wouldn't have time to react.

I don't think that excuses the lack of signficant acceleration/deceleration here. We saw better from the X-wings and Y-wings at the Battle of Yavin.

Of course we're also given some insight on maximum acceleration in the same episode. Anakin is trying to escape the advancing Ion blast and tells his men to give it all they've got, as they try to fly their ships out if said weapon's trajectory. But acceleration was not anywhere near the kilo-g area.

Which was interesting because of the Warsie claims about ST ships not being able to maneuver very well because of what happened in BoT with the Enterprise's attempt to escape the Romulan plasma weapon. Here in this TCW episode, we have top of the line starfighters (never mind the Republic transports) unable to escape an ion cannon bolt that, unlike the plasma torpedo of BoT, is not even capable of changing course or speed once fired! With the insane ICS-level accelerations, dodging the ion bolt would be a piece of cake.
-Mike

[l33telboi]

One of the highest accelerations is when Anakin joins the V-19 squadron, before attacking the six Munificents.
That said, pinch of salt with that cartoonesque CGI stuff. We've seen characters like Padmé do some weird fu.

That particular fighter had had its engine output increased, as said in the episode guide and hinted at in the episode itself. Originally, the episode was supposed to air with Anakin testing the engine output in the hangar, but they cut that scene for some reason.

[Who is like God arbour]

Only thing that matters in space is acceleration and deceleration, velocity is not as important.

I'm not sure, that this is correct.

The ability to accelerate or decelerate is limited by the thrust of an engine. Usually, engines produce thrust by the expulsion of a high-temperature, high-speed gaseous exhaust.

• • • I have read somewhere [1], that the "normal" rocket exhaust speed is only 4 km/s. But the exhaust of the VASIMR engine is with 300 km/s already 75 times as fast as normal engine exhaust.

Alone that means, that there is no further acceleration, when the speed of the thrust giving exhaust is reached.

But it goes further. Because, according to the equation of momentum, not only the speed of the exhaust is relevant, but also the mass of it.

If the mass of the exhaust is too low, although its speed is very high, the energy to accelerate a ship may be to small to gain further meaningful accelerations. There comes the point, where acceleration is mathematical still possible, but the acceleration is so low, that it is practically meaningless.

• • • We don't know, how fast the speed of the exhaust of an Y-Wing is supposed to be or how much mass it has. But observing their small acceleration abilities onscreen and seeing their relativ small engines, it is to conclude, that their maximum speed or the speed they can achieve in an acceptable time, can't be very high.

You need to remember that these vessels are piloted by humans, they can't zip by the Malevolence at near lightspeed, because then they wouldn't have time to react.

Correct.

But nobody has said, that they would have to fly near light speed. They could have choosen a speed twice, thrice or even ten times as fast as with which they have flown and still would have had enough time to react.

They have needed 1:30 minutes from the third scene above to the tenth scene above, meaning that they would have needed 1:30 minutes to cover less than 8 kilometres. That is a speed of less than 320 km/h - if I'm not mistaken.

Excuse me. But even the fighters and bombers of the World War II were faster than that and with computer aided targeting, they should have been able to target the bridge of the ship also with speeds far far higher than 320 km/h.

One of the highest accelerations is when Anakin joins the V-19 squadron, before attacking the six Munificents.

No spoiling!!!

I haven't seen that episode yet.

[l33telboi]

Only thing that matters in space is acceleration and deceleration, velocity is not as important.

I'm not sure, that this is correct.

The ability to accelerate or decelerate is limited by the thrust of an engine. Usually, engines produce thrust by the expulsion of a high-temperature, high-speed gaseous exhaust.

• • • I have read somewhere [1], that the "normal" rocket exhaust speed is only 4 km/s. But the exhaust of the VASIMR engine is with 300 km/s already 75 times as fast as normal engine exhaust.

Alone that means, that there is no further acceleration, when the speed of the thrust giving exhaust is reached.

But it goes further. Because, according to the equation of momentum, not only the speed of the exhaust is relevant, but also the mass of it.

If the mass of the exhaust is too low, although its speed is very high, the energy to accelerate a ship may be to small to gain further meaningful accelerations. There comes the point, where acceleration is mathematical still possible, but the acceleration is so low, that it is practically meaningless.

• • • We don't know, how fast the speed of the exhaust of an Y-Wing is supposed to be or how much mass it has. But observing their small acceleration abilities onscreen and seeing their relativ small engines, it is to conclude, that their maximum speed or the speed they can achieve in an acceptable time, can't be very high.

The maximum delta-v (how much a fighter can change its velocity) is at least above what's required to achieve escape velocity. The total delta-v for the vessels is not known however. That's why acceleration is more important, a ship can keep accelerating as long as it has fuel. And the fighters in Star Wars do have enough fuel to accelerate for quite a while.

Correct.

But nobody has said, that they would have to fly near light speed. They could have choosen a speed twice, thrice or even ten times as fast as with which they have flown and still would have had enough time to react.

True enough, I suppose. But it's a non-issue, because we know they can reach speeds far in excess of what they were flying. The only question is why they chose not to attack at a higher velocity. Personally I'd chalk it up to reaction time.

[Who is like God arbour]

The maximum delta-v (how much a fighter can change its velocity) is at least above what's required to achieve escape velocity.

Escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy. But a star ship or fighter with a respulsorlift does not have to have gravitational potential energy.

They would ascend automatically like a balloon, if they weigh nothing or nearly nothing and are displacing the air around them (as long as the displaced air is heavier than they are with an activated repulsorlift.)

The total delta-v for the vessels is not known however.

Correct. But, as I have already said, it can't be very high.

That's why acceleration is more important, a ship can keep accelerating as long as it has fuel.

No.

As I'm being told, depending on the derivation of the principle of linear momentum, a rocket can only reach a maximum speed, that is twice as fast as the speed of its exhaust.

And the fighters in Star Wars do have enough fuel to accelerate for quite a while.

Irrelevant if either the exhaust speed is low (no higher speeds are possible) or if the mass is low (not enough momentum is transferred to the ship to achieve meaningful accelerations).

For example, in theory a solar sail could achieve high relativistic speeds because it is impelled by photons, who are round about 300'000 km/s fast. But because their mass is low, the transferred momentum is also low, resulting in a low acceleration with which it would under conventional circumstances need two months to achieve a speed of 32 km/s [http://en.wikipedia.org/wiki/Solar_sail ... ht_Example].

But for fighters, only the speeds they can reach in short times is relevant. A fighter, that needs hours, days, weeks or months to achieve such a speed, is worthless.

True enough, I suppose. But it's a non-issue, because we know they can reach speeds far in excess of what they were flying.

Do we know that?

The only question is why they chose not to attack at a higher velocity.

I think, they haven't "choosen" to attack that slow. That would be stupid. The simple reason, why they haven't covered the length of the Malevolence with a higher speed to quickly reach the bridge (where they could have decelerated again) may be, that they simply were not able to achieve higher speeds, respective were not able to accelerate fast enough.

Personally I'd chalk it up to reaction time.

That's not plausible. The pilots were clones or Jedis with enhanced reaction time.

They should be able to react faster than a World War II pilot, especially with computer aided targeting.

Remember, they couldn't have flown faster than 320 km/h. The B17 has had a maximum speed of 462 km/h and a cruise speed of 293 km/h. Even the Junker Ju 87 has had a maximum speed of 390 km/h and the SBD Dauntless has had a maximum speed of 410 km/h. The later two are dive bombers, which are in their role comparable to the Y-wing.

[l33telboi]

Escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy. But a star ship or fighter with a respulsorlift does not have to have gravitational potential energy.

They would ascend automatically like a balloon, if they weigh nothing or nearly nothing and are displacing the air around them (as long as the displaced air is heavier than they are with an activated repulsorlift.)

As far as I know repulsorlifts don't work like that. They're just some form of generic anti-gravity tech, not something relying on buoyancy for levitation.

There's no reason to believe they don't have to use energy to levitate.

No.

As I'm being told, depending on the derivation of the principle of linear momentum, a rocket can only reach a maximum speed, that is twice as fast as the speed of its exhaust.

In space? No, I don't think so. As long as you keep throwing exhaust one way the ship will accelerate the other.

Irrelevant if either the exhaust speed is low (no higher speeds are possible) or if the mass is low (not enough momentum is transferred to the ship to achieve meaningful accelerations).

All theories have to be derived from evidence. There is no evidence for either of those theories. An equally valid theory we be assuming it’s all because of pink fairy dust.

I think, they haven't "choosen" to attack that slow. That would be stupid. The simple reason, why they haven't covered the length of the Malevolence with a higher speed to quickly reach the bridge (where they could have decelerated again) may be, that they simply were not able to achieve higher speeds, respective were not able to accelerate fast enough.

That explanation would quite frankly be even more stupid. Why would a futuristic society build thrusters that are far worse then modern ones? They did limit themselves to that speed for some reason. Reaction-time is my assumption as to why. But in the end it doesn’t matter why they limited themselves, just as long as you realize they did limit themselves.

Remember, they couldn't have flown faster than 320 km/h. The B17 has had a maximum speed of 462 km/h and a cruise speed of 293 km/h. Even the Junker Ju 87 has had a maximum speed of 390 km/h and the SBD Dauntless has had a maximum speed of 410 km/h. The later two are dive bombers, which are in their role comparable to the Y-wing.

You can't compare in-atmosphere flight with space-flight like that, especially not when one plane is a propeller driven vessel and the other uses rocket engines. Put a B17 in space and it wouldn't even be capable of traveling forwards. Put a modern Jet plane in space and its maximum velocity would be dictated only on how long it can keep accelerating.

[Mr. Oragahn]

Maximum speed in space is only defined by how long you have fuel to burn or the engines can work before mechanical failure or need for cooling down.

As for repulsors, as pointed out in the ICS thread, by Leo I think, Obi-Wan, in the novelization (or perhaps the movie, can't recall that crapfest) pulled out the plug and the droid fell. He put the plug back in and the droid resumed its course. There's then clear evidence that, at least, a continuous input of energy is needed.

[ILikeDeathNote]

That would be the novelization, I believe.

[Who is like God arbour]

1. Concerning the operating mode of repulsorlifts:
   
   • A repulsorlift does - as far as I know - not work with thrust but is a form of anti-gravity technology. If it, as such, negates gravity, it would negates the mass of the affected ship. And in that moment, buoyancy is valid. A ship with no or nearly no mass in an atmosphere would displace air and, as long as the air has a higher mass than the by the repulsorlift reduced mass of the ship, the ship will ascend like a balloon. That effect can be controlled by reducing or increasing the amount of negated mass.
     
     That the repulsorlift needs energy to do that - and that this energy would depend on the mass of the ship and its nearness to the gravity source (it has to negate the potential energy of the ship) is not contested.
     
     And even if a repulsorlift does not negate gravity or mass, it still would somehow affect gravity and allows a ship to push itself of a gravity source through this.
     
     With such a technology, it is not necessary any more to accelerate a ship with rockets to an escape velocity.
     
     And that was my point. The fact, that these ships are able to escape the gravity pull of a planet does not mean, that its engines have to be strong enough to accelerate the ship to an escape velocity. The repulsorlift can do most of the work.
2. Concerning the maximum achievable velocity of a rocket in space:
   
   • I was been told from a physicist, that, according to the Tsiolkovsky rocket equation, the maximum achievable velocity of a rocket is round about twice as fast as the effective exhaust velocity. More is impossible.
     
     But it is irrelevant, if significant higher speeds would be possible because, as I have said already, the acceleration is important or the amount of time, a rocket would need to achieve that speed. And one thing is indisputable: The acceleration of a rocket decreases with increasing speed. A rocket will need less time to accelerate from 0 to 1'000 km/s than from 1'000 km/s to 2'000 km/s, although the difference in speed is the same.
     
     And, as I have said also already: the relevant question is, how fast the Y-wings could have accelerated. And as it seems, they were not able to achieve significant higher speeds while attacking the Malevolence. Otherwise, they would have, if they are not totally stupid, chosen a speed far higher than the 320 km/h with which they have flown along the Malevolence.
3. Concerning in-atmosphere flight and space-flight:
   
   • I have not compared in-atmosphere flight with space-flight like that. These examples were only about the speed and the remaining reaction time of the pilots - not the fundamental differences propeller driven vessels and rocket driven vessels. You should try to remember your own posts or read a whole thread from time to time to refresh your memory:
     

     • • • True enough, I suppose. But it's a non-issue, because we know they can reach speeds far in excess of what they were flying. The only question is why they chose not to attack at a higher velocity. Personally I'd chalk it up to reaction time.

           That's not plausible. The pilots were clones or Jedis with enhanced reaction time.
           
           They should be able to react faster than a World War II pilot, especially with computer aided targeting.
           
           Remember, they couldn't have flown faster than 320 km/h. The B17 has had a maximum speed of 462 km/h and a cruise speed of 293 km/h. Even the Junker Ju 87 has had a maximum speed of 390 km/h and the SBD Dauntless has had a maximum speed of 410 km/h. The later two are dive bombers, which are in their role comparable to the Y-wing.

           You can't compare in-atmosphere flight with space-flight like that, especially not when one plane is a propeller driven vessel and the other uses rocket engines. Put a B17 in space and it wouldn't even be capable of traveling forwards. Put a modern Jet plane in space and its maximum velocity would be dictated only on how long it can keep accelerating.

     The pilot of a dive bomber, who is pouncing on its target on the ground, has had a higher speed relative to the target than these Y-Wings have had relative to the bridge of the Malevolence. And the pilot of the dive bomber would have to draw up its plane to prevent a crash. The Y-wings could simply have flown by on the sides of the bridge. And they were Clones and Jedis and have had computer aided targeting and advanced torpedos. I think, that they should be able to do more, than a WW II pilot.
4. Concerning the thrusters of a futuristic society and modern thrusters:
   
   • I propose you look at modern thrusters and now compare them to Star Wars thrusters. You will see, that the later have many advantages. They are smaller and weigh a lot less and need less fuel. And they are more reliable - they need less maintenance and don't tent to explode every 60 flights without proper reasons.
     
     But these advantages could have costed power - and that would be acceptable because with repulsorlifts, they wouldn't need so much raw power that our rockets are needing only to achieve escape velocity.
     
     If you ask me, I would choose the Star Wars thrusters - even if they are not able to create the same amount of thrust as our modern thrusters - every day, if I get also the repulsorlift technology.

[l33telboi]

A repulsorlift does - as far as I know - not work with thrust but is a form of anti-gravity technology. If it, as such, negates gravity, it would negates the mass of the affected ship.

And this is where you're wrong. There's no reason to assume that repulsorlifts decrease the mass of a vehicle. They're anti-gravity, or force projection technology, but they don't alter the vehicles mass. This becomes canonical if accept C-canon and consider the Starships of the Galaxy RPG, where it's said that the ion thrusters on the vessels use mass-manipulation technology to alter the mass of the vessel in relation to the exhaust. The repulsorlifts however - do not.

I was been told from a physicist, that, according to the Tsiolkovsky rocket equation, the maximum achievable velocity of a rocket is round about twice as fast as the effective exhaust velocity. More is impossible.

Seems that you've confused delta-v with acceleration. Either that or you're seriously suggesting that star wars fighters are only capable of accelerating the vessel to 8km/s and then runs out of fuel, being incapable of moving on its own afterwards. This is not what we see when they attack the Malevolence.

I suggest looking up the differences between delta-v and acceleration.

And one thing is indisputable: The acceleration of a rocket decreases with increasing speed.

No. Acceleration remains the same, unless we're talking velocities that go close to the speed of light. A ship traveling at 1,000m/s capable of 100m/s^2 acceleration is capable of that same acceleration at 10,000m/s.

And, as I have said also already: the relevant question is, how fast the Y-wings could have accelerated.

This we can easily gauge from the episode, yes. When the Y-wings try to escape the big pancake of doom.

But nobody has said, that they would have to fly near light speed. They could have chosen a speed twice, thrice or even ten times as fast as with which they have flown and still would have had enough time to react.

That's impossible to know for sure. We don't know how precise or synchronized they had to be when hitting the bridge. As such, reaction time is a good way to explain it. Because assuming the vessels can't go beyond 8km/s in space is IMO ridiculous.

If you ask me, I would choose the Star Wars thrusters - even if they are not able to create the same amount of thrust as our modern thrusters - every day, if I get also the repulsorlift technology.[/list][/list]

You can't base your theory on this. It's a way too haphazard and flimsy reasoning. Basically it amounts to "I think this would be plausible, so I shall assume it as fact."

[Mr. Oragahn]

A rocket with less fuel, but still consumes the same amount of fuel per second, should have an easier time pushing itself. Less fuel means lesser momentum for the same force. Now if for some reason, the combustible reaction's efficiency decreases, then that's something else.

Oh besides the physics are fucked up. At least in the movies, the explosions stick to the ships.
In TCW, there are trails of flames when ships are hit, and when the Malevolence is on fire, the flames and smoke rise... ....

I know that nukes and rocket trails are rarely correctly represented, but this is particularly horrible.
That and the absurd speed at which the pancake of doom moved when it neared the fighters, when we've seen it rush against capital ships.